Add -std=c++1z flag for C++17 features.

llvm-svn: 211030

clang/lib/Frontend/CompilerInvocation.cpp

@@ -1135,6 +1135,7 @@ void CompilerInvocation::setLangDefaults(LangOptions &Opts, InputKind IK,
   Opts.CPlusPlus = Std.isCPlusPlus();
   Opts.CPlusPlus11 = Std.isCPlusPlus11();
   Opts.CPlusPlus1y = Std.isCPlusPlus1y();
+  Opts.CPlusPlus1z = Std.isCPlusPlus1z();
   Opts.Digraphs = Std.hasDigraphs();
   Opts.GNUMode = Std.isGNUMode();
   Opts.GNUInline = !Std.isC99();